Days remain until the end of University of Mississippi Medical Center's contract with Blue Cross & Blue Shield of Mississippi. Both entities are preparing for the state's only academic medical center to no longer be in-network with the state's largest health insurer.

If a deal is not reached before Sunday, Blue Cross policyholders may still receive care from UMMC, which includes Batson Children's Hospital, but many will receive much higher out-of-pocket costs for services in the absence of negotiated discounts provided in contracts between hospitals and insurers.

Commissioner Mike Chaney sent a letter to both parties Friday asking them to meet with a professional mediator. Blue Cross responded Tuesday saying it agreed to a mediation conference but it would not be available for one before June 30. UMMC also said it would agree to a meeting.

In May after the state's only academic medical center announced its intention to terminate the contract, UMMC CEO Kevin Cook said patients who have Blue Cross insurance and are already being treated at UMMC for an established diagnosis would continue to receive care at the teaching hospital as in-network patients.

He also said UMMC would continue to treat emergencies of patients with Blue Cross insurance as in-network patients.

The changes do not apply to patients covered by the State and School Employees' Health Insurance Plan, because the state is self-insured and Blue Cross only administers the plan.

Here's how a bill is calculated: A hospital starts with a set price for every service determined by the provider's "chargemaster." These are usually extremely high charges that the hospital never intends to recoup.

If the insurance company is in-network, it has already negotiated a much lower "allowable amount" — the most the insurer will pay for that service.

The patient will first be responsible for meeting his or her deductible in the plan.

Then, if the policy includes a co-insurance — typically 20 percent of the allowable charges — the insurer will pay 80 percent and a patient will pay the rest.

A "balance bill" occurs when the insurance company and patient pay the allowable amount and the provider then bills the patient the difference between the initial charge and the amount paid.

These bills are prohibited by state law, even in the case of out-of-network providers.

But, if the provider refuses to take the insurance assignment altogether, it can bill a patient for the full amount specified in the chargemaster.

If UMMC leaves Blue Cross's network, the hospital plans to continue billing Blue Cross, which means patients won't have to file their own claims. But Cook said UMMC will not technically "accept the insurance assignment," which means it can bill the patient for the remaining amount — the large chargemaster rate.

Cook also said the hospital cannot, by law, provide discounts directly to patients who are insured.

A Monday Blue Cross statement indicated that it would be willing to continue making payments directly to UMMC if the medical center agrees not to balance bill.

"At a member's direction of payment, benefit payments will be made to UMMC with the expectation that, in accordance with Mississippi state law, UMMC will provide a payment hold harmless for our members and refrain from balance billing," the statement reads.

UMMC's primary problem with its Blue Cross contract is that it is 28 years old and allows the insurer to change the financial terms at any time without notification, Cook said in May.

Blue Cross, on the other hand, argued that UMMC just wants to receive special treatment and higher payments.

"UMMC wants to be treated differently from other Network Hospitals in this regard and has continued to leave reimbursement opportunities on the table in their resistance to partner with Blue Cross," Blue Cross spokeswoman Meredith Bailess said in May.

UMMC argued that it is special, as it's the only academic medical center, operates the only children's hospital and cares for some of the state's sickest patients.

The statement from Blue Cross & Blue Shield of Mississippi reads:

UMMC continues to be unwilling to work within their existing contract and has chosen to cancel their Participating Hospital Agreements with Blue Cross & Blue Shield of Mississippi beginning July 1, 2018. We are currently in non-network transition phase, and UMMC will be a non-network facility effective midnight June 30, 2018.

As always, our members are our top priority, and we will continue to act on their behalf to ensure they have access to quality, cost-effective care when and where it is needed. Blue Cross and Blue Shield members do not need to worry about the impact of UMMC’s action on their access to care as we will continue to provide Network-level benefits for medically necessary care received from UMMC and will work with our members to coordinate their care in the most appropriate setting.

We have informed our customers and Network Providers of the upcoming change and how it may impact them, specifically:

- All emergency care will continue to be covered at Network-level benefits.

- Network-level benefits will be paid for members currently receiving medically necessary care, those requiring ongoing follow-up or coordinated care at UMMC, and those patients who are newly referred and approved to use UMMC as their provider of choice. Benefits may vary according to a member’s specific benefit plan.

- At a member’s direction of payment, benefit payments will be made to UMMC with the expectation that, in accordance with Mississippi state law, UMMC will provide a payment hold harmless for our members and refrain from balance billing.

Again, we will continue working on our members' behalf to ensure they have access to the quality care they need, and Blue Cross and Blue Shield Network Providers across Mississippi, and in surrounding states, are available to serve our members.